Brake



Sept. 22, 1936. E. KAUFMANN BRAKE Filed Oct. 15, 1955 2 Sheets-Sheet 1 .Jzwezz for 29012.7(:

7532012222. m KM lilorzzez.

Patented Sept. 22-, 1 936 '1 j I UNITED STATES PATENT OFFICE Egon Kauimann, Mannheim, Germany, assignorto Deutsche Perrot Bremse G. in. b. 11., Mann'- heim-Friedrlchsleld, Germany Application October 15, 1935, Serial No. 45,111 Iiiv Germany September 19. 1934 7 Claims. (01. 188-'78) The present invention relates to brakes, 'par- A further object of the present invention is to ticularly two-block brakes, for automobiles in provide a brake which is simple to manufacture which the blocks can, within limits, freely and cirand having a very small number of individual cumferentially move between two thrust blocks parts and great, equal, and self-increasing brake and in which the blocks are forced on to the brake power for all blocks. 5 drum by means of spreading levers which engage Further and other objects of the present insaid blocks. vention will be hereinafter set forth in the ac- An object of this invention resides in the pro- 'companying specification and claims and shown vision of a brake system of the type described in in the drawings which, by way of illustration, the paragraph next above in which the spreadshow what I now consider to be a preferred em- 10 ing levers are built as elbow levers the long arms bodiment of my invention. of which extend in circumferential direction, In the drawings:

overlap one another, and are operated simulta- Fig. 1 isa top view of a brake mechanism acneously by an operating mechanism common to cording to my invention. lo both levers" Fig. 2 is a perspective showing of a spreading it Another object'of the present invention is to lever according to my invention. provide a brake of the type described in the, Fig. 3 is apart sectional view taken along lines foregoing paragraphs in which the long arms of 33 in Fig. 1 and looking in the direction of the the spreading levers are provided with circular arrows.

2 curves having the same center point as the brake Fig. 4 is a top view of the operating lever as- 0 drum and on which the brake operating mechasembly as mounted on the back plate. nism acts and which permit circumferential Like parts are designated by like numerals in movement of the blocks with respect to the brake all the figures of the drawings. The lead lines drum, for example, when the direction of rotato elements shown in dotted lines are dotted.

tion of the drum is changed, due to which ar- R f r n m r p i y to the r win s: 25 rangement a change of the position of the brake 35 is the brake drum. I is the back plate to which blocks does not affect the brake operating mechatwo bolts 2 and 2 are fixed which serve as thrust nism, and an undesirable brake action or jambing blocks for the two brake blocks 3 and 4. Proof the brake, for example, when changing over jections 20 and 2| and 20' and 2! of the spreadfrom forward to return driving is made imposing levers 5 and G are located between the ends 30 sible. of blocks 3 and 4. The long arms of levers 5 and A further object of this invention is the pro- 6 are curved and follow substantially a circle vision of a brake system of the type described in which is concentric with the brake drum. These the paragraphs next above in which the point long arms point towards one another, and the at which the operating mechanism acts on'the ends of the levers overlap one another. Each 35 long arms of the spreadinglevers is solocated that lever is provided with a curved gliding or rolling the spreading power transmitted to the brake surface 5' and 6', respectively; dog 9, which is shoes is equal or almost equal at the prevailpart of the operating lever l, rests against these ing direction of rotation of the brake drum, 1. e., curves. If the direction of rotation and the posi- 40 that,-when the car goes forwards, an equal action of the brake blocks are changed,jthe curves 40 tion of both brake shoes is assured. 5 and 6' run along dog 9 without affecting the Another object of this invention resides in the brake operating mechanism. a provision of a brake system of the type described Operating lever I swings about bolt 8 which in the foregoing paragraphs in which the springs is'fixed to the back plate I. A conventional brake by means of which the brake shoes are pulled tooperating member 24 is connected to the free end 45 wards the thrust blocks are so adjusted that, at 23 of lever 8. theprevailing direction of rotation of the brake Brake block 3 is resiliently pulled towards the drum, the individual brake shoes are brought onto' thrust blocks 2 and 2' by means of springs ll the drum gradually and counter to the direction and I2 spring li'ismade stronger than spring I l of rotation of the'drum, due to which iact a-confor reasons which will be described later. Like- 50 siderably greater braking action is obtained as wise, block I. is held to thrust block 2 by means compared with that of a conventional two-block of spring I! and to thrust block 2' by means of brake, and the brake action is in proportion to spring I I. One end of springs l'l and l2' is conthe pressure exerted on the foot pedal, and lambnected to block 3, the other end of spring II is mg of the brake is practically eliminated. connected to the bent up part 25 of plate. 55 i 4 at point I4.

which is held to bolt 2 by means of the split pin 21; the other end of spring I2 is connected to bent up part 28 of plate 29 whichis held to bolt 2' by split pin 21'. Bent up part 25 is located closer to the center of the brake and part 28 more at the outside of the brake. One end of spring I2 is connected to block 4 and the other end to the outer bentup part 30 of plate 26. One end ofspring H is connected to block 4 and the other end to the inner'bent up part SI of plate 29.

The long arms of the two spreading levers 5 and 6 have such configuration and the dog 9, by means of which operating lever 1 engages said long arms, has such position that, at the prevail ing direction of rotation, the forces transmitted to blocks 3 and 4 are exactly or almost equal, so that both blocks participate in like manner on the brake action, and the wear is the same for both blocks. The following consideration serves to find the correct position for the dog 9:

.If the brake drum rotates in the prevailing direction which is indicated by arrow 22 and the brake is applied, block 3 is lifted from bolt 2 and block 4 from bolt 2'. In order to assure this mode of operation, springs II and II are made weaker than springs l2 and 12. Spring l2 and I2 hold block 3 to bolt 2' and block 4 to bolt 2, and block 3 is lifted from bolt 2 against the action of the weaker spring I l and block 4 against the action of the weaker spring II from block 2' when the brake is applied. The spreading lever 5 thus turns about point l4 where projection abuts against the outer end of block 4 and presses at point l3 with projection 2| against the inner end of block 3 and removes it from thrust block 2. The leverage is determined by the distances between point III, which is the point of action of dog 9 on lever 5, and point M4 and between point 13 and I4.

With block 4 and spreading lever 6 conditions are different. In order to apply block 4 in a direction counter to the prevailing direction of rotation of the brake drum to said drum, lever 6 must swing about point l3 thereby lifting block The leverage is determined by the distances between points In and i3 and points The position of dog 9 with respect to levers 5 and 6 must be so that an absolutely equal momentum acts on both brake blocks and not only an equal effect of the brake blocks onto the drum is produced but also equal wear of the linings 33 and 34 of blocks 3 and 4 is assured. Therefor this position must be determined by taking into account the leverages described in the two paragraphs next above and the movement of levers 5 and 6 about thrust blocks 2 and 2' and their points of action on the brake blooks4 and 3. If the point of action of dog 9 is correctly determined, the brake acts equally on the whole circumference of the brake drum at the prevailing direction of rotation of the brake drum.

While I believe the above described embodiments of my invention to be preferred embodiments, I wish it to be understood that I do not desire to be limited to the'exact details of design and construction shown and described, for obvious modifications will occur to a person skilled in the art.

What is claimed as new is:

1. A brake comprising a-brake drum, a plurality of brake shoes having pairs of disconnected adjacent ends, applying means located within said drum for spreading said pairs of ends, said applying means comprising pairs of overlapping lever arms having a curved configuration which is substantially concentric with said brake drum.

2. A brake comprising a brake drum, a plurality oibrake shoes having pairs of disconnected adjacent ends, applying means for spreading said pairs of ends, said applying means comprising lever arms having a curved configuration which is substantially concentric with said brake drum, said lever arms pointing towards and overlapping one another.

3. A brake comprising a brake drum, a plurality of brake shoes having pairs of disconnected adjacent ends, applying means for spreading said pairs of ends, said applying means comprising two lever arms having a curved configuration which is substantially concentric with said brake drum, said lever arms pointing towards one another and having overlapping parts, and an operating member engaging both of said levers at said overlapping parts.

4. A brake comprising a brake drum, a plurality of brake shoes having pairs of disconnected adjacent ends, applying means for spreading said .pairs of ends, said applying means comprising two lever arms having a curved configuration which is substantially concentric with said brake drum, said lever arms pointing towards one another and having overlapping parts, and an operating member having means adapted to abuttingly engage both of said levers at said overlapping parts.

5. A brake comprising a brake drum, a plurality of brake shoes having pairs of disconnected adjacent ends, applying means for spreading sai'd pairs of ends, said applying means comprising two lever arms provided with curves which are substantially concentric with said brake drum, said lever arms pointing towards one another and said curves overlapping one another, and an operating member simultaneously engaging said curves of both of said lever arms for opcrating said brake.

6. A brake comprising a plurality of brake shoes having pairs of disconnected adjacent ends, applying means for spreading said pairs of ends, said applying means comprising two lever arms adapted to swing about points adjacent to said ends and pointing towards and overlapping one another, and an operating member simultaneously engaging both of said lever arms, the place of engagement of said operating member and pointing towards one another and having overlapping parts, and an operating lever engaging both of said levers at said overlapping parts, said lever arms and said operating lever swinging towards the center of said brake when the brake shoes are applied and swinging from the center of said brake when the brake shoes are released.

EGON KAUFMANN. 

